Russian Journal of Non-Ferrous Metals最新文献

The surface mechanical properties of AlSi10Mg alloy produced by selective laser melting (SLM) with different laser scan angles α (45°, 67°, 90°) were investigated. Instrumented indentation revealed differences in nanohardness H and elastic modulus E: the α = 90° variant provided the highest nanohardness H = 1.57 ± 0.35 GPa and the lowest maximum indenter penetration depth h_max = 1.2 µm, whereas the α = 67° variant exhibited the highest elastic modulus E = 46.4 ± 3.19 GPa. Scratch testing showed the largest groove depth for the α = 45° sample—8.1 µm, with a friction coefficient μ = 0.79; the smallest groove depth for α = 67°—6.4 µm, μ = 0.73; and intermediate values for α = 90°—6.9 µm, μ = 0.74. Scanning electron microscopy of the hardest sample (α = 90°) revealed surface porosity with predominantly elongated defects: 81% of pores <150 µm, a pore density of 16 pores/mm², a low fraction of pores <50 µm (18.8%), and isolated large cavities up to 457 µm.

The paper examines the phenomenon of acoustic emission (AE) during monotonic deformation (compression) of magnesium alloy MgZnCa samples in five different structural states: cast, extruded, and all-round isothermal forging (isothermal multidirectional forging (IMF), IMF with subsequent extrusion, IMF with subsequent rolling. When deforming samples in the region of elastic–plastic transition, a traditional peak in the power of the AE signal is observed. The sources of acoustic emission are relaxation processes in the crystal lattice associated with the operation of deformation systems of slip and twinning in crystals. It is known that an increase in grain size increases, and hardening (work hardening) decreases the magnitude of the peak power AE; it is also well known that the intensity of AE depends on the activation mode of the deformation systems of the crystal lattice. The probability of activation of deformation systems is determined by the Schmidt factor, which was calculated for each grain of the microstructural map of the test metal, obtained by scanning electron microscopy with electron backscatter diffraction analysis. Based on these data, the proportion of material for which the current stress level exceeds the shear stresses of activation of deformation systems was calculated. It was found that for all five different structural states and for all orthogonal directions of load application, the peak power value of the acoustic emission signal, normalized to the grain size and surface area of the sample, is functionally related to the proportion of active grains.

In this study, a multi-objective inverse identification framework is developed to simultaneously determine the material flow stress parameters and the friction condition for AA6061–T6 under cold compression. The proposed approach combines a single compression experiment with systematic finite element simulations organized through a Box–Behnken design, surrogate modeling of numerical responses, and Pareto-based multi-objective optimization using the NSGA-II algorithm. The inverse identification is based on force–time and geometric responses extracted from the compression test and corresponding simulations. Response surface models are constructed and subsequently employed as surrogate models in the multi-objective optimization procedure, enabling robust exploration of the admissible parameter space. The identified results demonstrate strong and stable convergence of the Swift hardening parameters for AA6061–T6. The strength coefficient K is identified within a narrow range of approximately 358.52–361.13 MPa, while the strain-hardening exponent n converges to a value close to 0.088. The Coulomb friction coefficient m consistently converges toward the lower bound of the investigated domain, reaching a unique value of approximately 0.05. This value is physically reasonable for lubricated cold compression of aluminum alloys and is interpreted as a representative friction level constrained by the experimental observability of the present compression-based inverse framework. The results confirm that reliable and physically consistent identification of both material hardening behavior and friction conditions can be achieved from a single compression test by combining finite element simulations, design of experiments, and Pareto-based multi-objective optimization.

This study investigated the enhancement of mechanical and physical properties of 6061 aluminum alloy by employing friction stir additive manufacturing (FSAM), producing a multilayer composite reinforced with eggshell and graphene particles. A square high-speed steel tool ensured homogeneous dispersion of these reinforcements in the matrix. By varying reinforcement proportions, the composite attained significant property improvements: hardness increased by 26.7%, tensile strength by 24.2%, and compressive strength by 11% when using 4.0 wt % eggshell and 6.0 wt % graphene. Corrosion testing showed excellent resistance, with a negligible weight loss (0.2 g) after 90 h in NaCl solution—consistent with AA6061’s natural high corrosion resistance. The material also demonstrated negligible thermal expansion. Fractographic analysis showed brittle fracture characteristics, likely due to the presence of reinforcement particles, which aligns with stated trends for metal matrix composites. These results reveals FSAM’s ability to evenly distribute reinforcements, refine grain structure, and significantly enhance strength, hardness, and corrosion resilience, positioning these composites for advanced engineering applications.

The influence of the Hf/Zr ratio on the structure, martensitic transformations, and functional properties of cast senary medium-entropy Ti–Hf–Zr–Ni–Cu–Co shape memory alloys with a total Hf+Zr concentration of 10 at % was studied. It was found that the alloy structure did not depend on the Hf/Zr ratio. All alloys underwent the B2 ↔ B19′ martensitic transformation regardless of the Hf/Zr ratio. An increase in the Zr concentration from 2.5 to 7.5 at % decreased the martensitic transformation temperatures by 10–15°C. Mechanical tests carried out in the austenitic and martensitic states showed that on an increase in Zr concentration, the martensite reorientation stress decreased, whereas the yield limit for dislocation slip in the austenitic phase increased. A study of the recoverable strain variation on cooling and heating under stress showed that its maximum value was equal to 6% and did not depend on the Hf/Zr ratio. The recovery coefficient increased with a rise in the Zr concentration due to a suppression of the dislocation slip on cooling under stress.

During the production of ferromanganese and ferrosilicomanganese alloys, large amounts of dust containing manganese and valuable non-ferrous metals such as zinc and lead are generated. Efficient utilization of this dust is essential for resource recovery and environmental protection. This study investigates processing approaches for zinc- and lead-rich and zinc- and lead-poor dusts formed during manganese ferroalloy smelting at the Taraz Metallurgical Plant (Kazakhstan). Laboratory and semi-industrial experiments were performed using electric smelting and Waelz processing of briquetted dust with carbonaceous reducing agents. Thermodynamic modeling with the HSC-6 software was applied to determine equilibrium conditions and metal distribution. Smelting of lead-rich dust (28.6% PbO) yielded crude lead (92–95% Pb), lead–zinc sublimates (15–26% Zn, 6–17% Pb), and manganese-rich slag (45–46% MnO). Waelz processing of zinc-rich dust (31.1% ZnO) produced sublimates with 53–55% Zn and 6–7% Pb, and clinker with 38–41% MnO. Metal recoveries reached 84–98% Zn, 91–97% Pb, and 82–99% Mn. The developed technological schemes ensure efficient, environmentally safe recovery of metals and complete utilization of ferroalloy production residues.

A new hydro-electrometallurgical process to recover the lead from the damped lead battery paste by sodium hydroxide leaching and electrowinning is proposed. PbO₂-bearing damped lead battery paste is first reduced with ferrous sulfate solution and PbSO₄ in leaching residue is desulfurized with sodium hydroxide. The desulfurized paste is leached with sodium hydroxide and metallic lead is recovered in sodium plumbate solution based on alkaline by electrowinning. Several factors such as stirring speed, sodium hydroxide concentration, temperature and liquid to solid ratio were considered in leaching process of the desulphurization paste contained mainly Pb(OH)₂ on the lead extraction and lead concentration. A lead extraction of more than 90% is obtained in optimal condition of this step. The factors such as lead content and sodium hydroxide content, temperature and current density on the cathodic current efficiency and electric power consumption were considered. The cathodic current efficiency and electric power consumption were more than 96% and less than 0.64 kWh/kg in optimal electrolytic condition, respectively.

This study proposes an integrated hydrometallurgical route for the valorization of high-iron jarosite leach residues generated during zinc production. The investigated residue contains significant amounts of zinc (≈17.82 wt %) and iron (≈20.82 wt % as Fe₂O₃), with trace silver (≈409 ppm). Zinc extraction was first performed by controlled sulfuric acid leaching under systematically varied operating parameters using a mechanically agitated reactor. Under optimized conditions (pH = 1.8 ± 0.1, T ≈ 70°C, t ≈ 90 min, S/L = 0.10 g mL^–1 and [H₂SO₄]₀ = 250 g L^–1), zinc recovery reached approximately 92%. Kinetic analysis revealed a two-stage dissolution mechanism characterized by an initial surface-reaction-controlled regime followed by diffusion limitation due to progressive jarosite passivation, consistent with the Shrinking Core Model (SCM). Silver recovery from the zinc-depleted residue was subsequently investigated using thiourea as a non-cyanide lixiviant. Ag extraction reached approximately 20% under the optimized flowsheet conditions and increased up to 35–42% when thiourea concentration was raised to 0.5–1.0 M in acidic medium. The results demonstrate the technical feasibility of combined Zn–Ag recovery from jarosite-rich residues, providing a practical and environmentally sustainable route for the valorization of hydrometallurgical wastes and offering a basis for future pilot-scale applications.

NiTi wire coating was applied to titanium alloy (Ti–6Al–4V) to develop its surface mechanical characteristics using TIG heat source. The TIG cladding process was used to melt a 1 mm diameter NiTi wire, creating a clad layer on the Ti–6Al–4V substrate. The present study investigates the effect of varying TIG welding currents (45–65 A) on the clad surface, focusing on changes in microstructure, phase evolution, hardness, and wear resistance. At a current of 45 A, the clad layer exhibited a peak average hardness of 754 HV, which is approximately 2.4 times higher than that of the base Ti–6Al–4V alloy. EDS and XRD analyses identified NiTi, NiTi₂, unreacted Ti, and TiAl₃, phases, along with intermetallic compounds, which contributed to the enhanced mechanical characteristics. The NiTi clad layer experienced wear height losses between 0.042 and 0.160 mm, whereas the Ti–6Al–4V substrate recorded a greater loss of 0.38 mm, demonstrating that the NiTi coating offered up to nine times improved wear resistance.

The work shows the influence of variations in the conditions of heat treatment of the multicomponent alloy LMtsAZhKS 70-7-5-2-2-1 on the phase composition, microstructure and tribological properties. The study was conducted by comparing the estimated characteristics of the alloy after its quenching in various cooling media: water, oil and water–polymer solutions with concentrations of 5, 10, and 20%. The hardness, friction coefficient, volumetric wear and structure of the original materials and tribomodified layers were assessed. The results showed that quenching in water–polymer media with a concentration of 10% and higher fixes a metastable microstructure with a fraction of α-phase of 2–5%, providing strengthening up to 20% and increasing wear resistance by more than 2 times. A linear dependence of volumetric wear on the fraction of α-phase was established. Under load, gradual destruction of β'-phase occurs with a BCC → FCC transformation. The formation of tribomodified words occurs with the redistribution of alloying elements. The mechanism of formation of tribomodified layers is described. The obtained results complement the understanding of phase transitions in brasses under the influence of operational loads.